/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.client.standard;

import java.util.Arrays;
import java.util.List;

import javax.websocket.ClientEndpointConfig;
import javax.websocket.ClientEndpointConfig.Configurator;
import javax.websocket.ContainerProvider;
import javax.websocket.Decoder;
import javax.websocket.Encoder;
import javax.websocket.Endpoint;
import javax.websocket.Extension;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.core.task.SimpleAsyncTaskExecutor;
import org.springframework.core.task.TaskExecutor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.socket.client.ConnectionManagerSupport;
import org.springframework.web.socket.handler.BeanCreatingHandlerProvider;

/**
 * A WebSocket connection manager that is given a URI, an {@link Endpoint}, connects to a
 * WebSocket server through the {@link #start()} and {@link #stop()} methods. If
 * {@link #setAutoStartup(boolean)} is set to {@code true} this will be done automatically
 * when the Spring ApplicationContext is refreshed.
 *
 * @author Rossen Stoyanchev
 * @see AnnotatedEndpointConnectionManager
 * @since 4.0
 */
public class EndpointConnectionManager extends ConnectionManagerSupport implements BeanFactoryAware {

    @Nullable
    private final Endpoint endpoint;

    @Nullable
    private final BeanCreatingHandlerProvider<Endpoint> endpointProvider;

    private final ClientEndpointConfig.Builder configBuilder = ClientEndpointConfig.Builder.create();

    private WebSocketContainer webSocketContainer = ContainerProvider.getWebSocketContainer();

    private TaskExecutor taskExecutor = new SimpleAsyncTaskExecutor("EndpointConnectionManager-");

    @Nullable
    private volatile Session session;


    public EndpointConnectionManager(Endpoint endpoint, String uriTemplate, Object... uriVariables) {
        super(uriTemplate, uriVariables);
        Assert.notNull(endpoint, "endpoint must not be null");
        this.endpoint = endpoint;
        this.endpointProvider = null;
    }

    public EndpointConnectionManager(Class<? extends Endpoint> endpointClass, String uriTemplate, Object... uriVars) {
        super(uriTemplate, uriVars);
        Assert.notNull(endpointClass, "endpointClass must not be null");
        this.endpoint = null;
        this.endpointProvider = new BeanCreatingHandlerProvider<>(endpointClass);
    }


    public void setSupportedProtocols(String... protocols) {
        this.configBuilder.preferredSubprotocols(Arrays.asList(protocols));
    }

    public void setExtensions(Extension... extensions) {
        this.configBuilder.extensions(Arrays.asList(extensions));
    }

    public void setEncoders(List<Class<? extends Encoder>> encoders) {
        this.configBuilder.encoders(encoders);
    }

    public void setDecoders(List<Class<? extends Decoder>> decoders) {
        this.configBuilder.decoders(decoders);
    }

    public void setConfigurator(Configurator configurator) {
        this.configBuilder.configurator(configurator);
    }

    public WebSocketContainer getWebSocketContainer() {
        return this.webSocketContainer;
    }

    public void setWebSocketContainer(WebSocketContainer webSocketContainer) {
        this.webSocketContainer = webSocketContainer;
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        if (this.endpointProvider != null) {
            this.endpointProvider.setBeanFactory(beanFactory);
        }
    }

    /**
     * Return the configured {@link TaskExecutor}.
     */
    public TaskExecutor getTaskExecutor() {
        return this.taskExecutor;
    }

    /**
     * Set a {@link TaskExecutor} to use to open connections.
     * By default {@link SimpleAsyncTaskExecutor} is used.
     */
    public void setTaskExecutor(TaskExecutor taskExecutor) {
        Assert.notNull(taskExecutor, "TaskExecutor must not be null");
        this.taskExecutor = taskExecutor;
    }

    /**
     * 打开链接
     */
    @Override
    protected void openConnection() {
        this.taskExecutor.execute(() -> {
            try {
                if (logger.isInfoEnabled()) {
                    logger.info("Connecting to WebSocket at " + getUri());
                }
                Endpoint endpointToUse = this.endpoint;
                if (endpointToUse == null) {
                    Assert.state(this.endpointProvider != null, "No endpoint set");
                    endpointToUse = this.endpointProvider.getHandler();
                }
                ClientEndpointConfig endpointConfig = this.configBuilder.build();
                this.session = getWebSocketContainer().connectToServer(endpointToUse, endpointConfig, getUri());
                logger.info("Successfully connected to WebSocket");
            }
            catch (Throwable ex) {
                logger.error("Failed to connect to WebSocket", ex);
            }
        });
    }

    /**
     * 关闭链接
     * @throws Exception
     */
    @Override
    protected void closeConnection() throws Exception {
        try {
            Session session = this.session;
            if (session != null && session.isOpen()) {
                session.close();
            }
        }
        finally {
            this.session = null;
        }
    }

    @Override
    protected boolean isConnected() {
        Session session = this.session;
        return (session != null && session.isOpen());
    }

}
